MEXICO CITY -- Mexico slapped preliminary tariffs of as much as 215% on U.S. beef imports, saying that U.S. meatpackers were selling everything from fine cuts to tripe, tongue and liver at artificially low prices here.

Mexican trade authorities took the extraordinary step of singling out four big U.S. meatpackers for less severe treatment. In several product categories, lower tariffs will be applied to goods shipped by Excel Corp., IBP Inc., Farmland National Beef Packing Co. and ConAgra Inc., because Mexican trade...